Portable light box



FIG. 1 is a rear perspective view of a portable light box showing my new design in the elevated position;

FIG. 2 is a top plan view thereof in the closed position;

FIG. 3 is a right side elevational view of FIG. 2;

FIG. 4 is a rear elevational view thereof;

FIG. 5 is a bottom plan view thereof; and

FIG. 6 is an inverted front elevational view thereof. 

The ornamental design for a portable light box, as shown and described. 